The CT Scanner is the abbreviation of computer tomography scanner. The invention of CT Scanner in 1970 was made possible by a previously established insight and development of the dedicated minicomputers.

Block Diagram of the CT Scanner

Operations of CT Scanner

High voltage supply drives the x-ray tube that can be mechanically
rotated along the circumference of a gantry.

Patient is lying in a tube in the center of gantry.

The X-rays passes through the patient and produces an image on
detectors, which are fixed in a place around the circumference of the
gantry in a large quantity.

Microcomputer sense the position of tube in the gantry and samples
the output of the detector scanner which is opposite to the x-ray
tube.

A calculation based on the data of a computer scan of the tube is
made by the computer.

The O/P unit then produces a visual image of a transverse plane
cross the section of patient.

The output may be displayed on the cathode ray tube or photographed with a camera to produce a hard copy record.

Detector operation and construction

Detectors consist of ionization chambers filled with a gas such as xenon, sealed at both ends and having two conductors forming a capacitor on the sides. A high DC voltage is applied to the capacitors an x-rays entry. The chamber ionizes the xenon item causing it to migrate to capacitor plate and causing a current in the high voltage load. This current is proportional to the radiation and is fed to the computer as data for computing the image.

The advanced model of CT scanner create image at an angle other than 90° by tilting the gantry.

Application of CT Scanner

Its major application is in medical field. In medical, it is used to
Detect the injury in the human brain